Question: Write the charge-balance equations for the

> A solution was prepared by dissolving 7.48 g of KCl # MgCl2 # 6H2O 1277.85 g>mol2 in sufficient water to give 2.000 L. Calculate a. The molar analytical concentration of kcl.Mgcl2 in this solution. b. The molar concentration of Mg21. c. The molar conc

> a. A 0.1527-g sample of primary-standard AgNO3 was dissolved in 502.3 g of distilled water. Calculate the weight molar concentration of Ag1 in this solution. b. The standard solution described in part (a) was used to titrate a 25.171-g sample of a KSCN

> a. A 0.3147-g sample of primary-standard-grade Na2C2O4 was dissolved in H2SO4 and titrated with 31.67 mL of dilute KMnO4: 2MnO4 2 1 5C2O4 22 1 16H1 S 2Mn21 1 10CO21g2 1 8H2O Calculate the molar concentration of the KMnO4 solution. b. The iron in a 0.

> A 0.1475-M solution of Ba1OH22 was used to titrate the acetic acid (60.05 g/mol) in a dilute aqueous solution. The following results were obtained. a. Calculate the mean w/v percentage of acetic acid in the sample. b. Calculate the standard deviation

> The ethyl acetate concentration in an alcoholic solution was determined by diluting a 10.00-mL sample to 100.00 mL. A 20.00-mL portion of the diluted solution was refluxed with 40.00 mL of 0.04672 M KOH: CH3COOC2H5 + OH2 → CH3COO2 + C2H5OH After cooling,

> What mass of AgI can be produced from a 0.512-g sample that assays 20.1% AlI3?

> A solution of Ba1OH22 was standardized against 0.1215 g of primary-standard-grade benzoic acid, C6H5COOH 1122.12 g>mol2. An end point was observed after addition of 43.25 mL of base. a. Calculate the molar concentration of the base. b. Calculate the st

> The thiourea in a 1.455-g sample of organic material was extracted into a dilute H2SO4 solution and titrated with 37.31 mL of 0.009372 M Hg21 via the reaction 41NH222CS + Hg21 → 31NH222CS44Hg21 Find the percentage of 1NH222CS 176.12 g>mol2 in the sample.

> The arsenic in a 1.203-g sample of a pesticide was converted to H3AsO4 by suitable treatment. The acid was then neutralized, and 40.00 mL of 0.05871 M AgNO3 was added to precipitate the arsenic quantitatively as Ag3AsO4. The excess Ag1 in the filtrate an

> Three different analytical methods are compared for determining Ca in a biological sample. The laboratory is interested in knowing whether the methods differ. The results shown next represent Ca results in ppm determined by an ion-selective electrode (IS

> A 100.0-mL sample of spring water was treated to convert any iron present to Fe21. Addition of 25.00 mL of 0.002517 M K2Cr2O7 resulted in the reaction 6Fe21 + Cr2O7 22 + 14H1 → 6Fe31 + 2Cr31 + 7H2O The excess K2Cr2O7 was back-titrated with 8.53 mL of 0.0

> A 4.912-g sample of a petroleum product was burned in a tube furnace, and the SO2 produced was collected in 3% H2O2. Reaction: SO21g2 + H2O2 → H2SO4 A 25.00-mL portion of 0.00873 M NaOH was introduced into the solution of H2SO4, following which the exces

> What CrO42- concentration is required to a. Initiate precipitation of Ag2CrO4 from a solution that is 5.24 × 10-3 M in Ag+? b. Lower the concentration of Ag+ in a solution to 7.82 × 10-7 M?

> Titration of the I2 produced from 0.1142 g of primary-standard KIO3 required 27.95 mL of sodium thiosulfate. IO3 2 + 5I2 + 6H1 → 3I2 + 3H2O I2 + 2S2O3 22 → 2I2 + S4O6 22 Calculate the concentration of the Na2S2O3.

> Titration of 50.00 mL of 0.04715 M Na2C2O4 required 39.25 mL of a potassium permanganate solution. 2MnO4 2 + 5H2C2O4 + 6H1 → 2Mn21 + 10CO21g2 + 8H2O Calculate the molar concentration of the KMnO4 solution.

> The week 3 measurement in the data set of Problem 5-16 is suspected of being an outlier. Use the Q test to determine if the value can be rejected at the 95% confidence level. Answer

> Treatment of a 0.3500-g sample of impure potassium chloride with an excess of AgNO3 resulted in the formation of 0.3846 g of AgCl. Calculate the percentage of KCl in the sample.

> Write an equation showing how the mass of the substance sought can be converted to the mass of the weighed substance on the right.

> Suggest a precipitation method for separation of K+ from Na+ and Li+.

> What is peptization, and how is it avoided?

> Suggest a method by which Pb21 can be precipitated homogeneously as PbS.

> A 0.4126-g sample of primary-standard Na2CO3 was treated with 40.00 mL of dilute perchloric acid. The solution was boiled to remove CO2, following which the excess HClO4 was back-titrated with 9.20 mL of dilute NaOH. In a separate experiment, it was esta

> Calculate the solubility of the solutes in Problem 7-10 for solutions in which the cation concentration is 0.030 M.

> Why do molar concentrations of some species appear as multiples in charge-balance equations?

> In the margin note on page 215, we suggest that the term mass-balance equation may be something of a misnomer. Using a specific chemical system, discuss mass balance and show that mass balance and concentration balance are equivalent.

> Find the amount in millimoles of the indicated species in a. 12.92 g of NaHCO3 b. 57 mg of MgNH4PO4. c. 850 mg of P2O5. d. 40.0 g of CO2.

> Define a. Molar mass. b. Millimole. c. Millimolar mass. d. Parts per billion.

> Why are simplifying assumptions in equilibrium problems restricted to relationships that are sums or differences?

> The phosphorous content in ppm was measured for three different soil locations. Five replicate determinations were made on each soil sample. A partial ANOVA table follows: a. Fill in the missing entries in the ANOVA table. b. State the null and alternati

> Demonstrate how the sulfide ion concentration is related to the hydronium ion concentration of a solution that is kept saturated with hydrogen sulfide.

> Calculate the molar solubility of Tl2S as a function of pH over the range of pH 10 to pH 1. Find values at every 0.5 pH unit, and use the charting function of Excel to plot solubility versus pH.

> In contrast to many salts, calcium sulfate is only partially dissociated in aqueous so Kd = 5.2 × 10-3 The solubility-product constant for CaSO4 is 2.6 × 10-5 . Calculate the solubility of CaSO4 in (a) water and(b) 0.0100 M Na

> The equilibrium constant for formation of CuCl2 2 is given by What is the solubility of CuCl in solutions having the following analytical NaClconcentrations: a. 5.0 M? b. 5.0 × 10-1 M? c. 5.0 × 10-2 M? d. 5.0 × 1

> A 0.5002-g sample that assayed 96.4% Na2SO4 required 48.63 mL of a barium chloride solution. Reaction: Ba21 + SO4 22 → BaSO4(s) Calculate the analytical molar concentration of BaCl2 in the solution.

> What mass of AgBr dissolves in 200 mL of 0.200 M NaCN?

> Using 1.0 × 10-6 M as the criterion for quantitative removal, determine whether it is feasible to use a. SO4 22 to separate Ba21 and Sr21 in a solution that is initially 0.030 M in Sr21 and 0.15 M in Ba21. b. SO4 22 to separate Ba21 and Ag1 in a soluti

> Silver ion is being considered for separating I- from SCN- in a solution that is 0.040 M in KI and 0.080 M in NaSCN. a. What Ag1 concentration is needed to lowerthe I- concentration to 1.0 × 10-6 M? b. What is the Ag1 concentration of the solution when

> A solution is 0.030 M in Na2SO4 and 0.040 M in NaIO3.To this is added a solution containing Ba21. Assuming that no HSO4 - is present in the original solution, a. which barium salt will precipitate first? b. what is the Ba21 concentration as the first p

> Dilute NaOH is introduced into a solution that is 0.050 M in Cu21 and 0.040 M in Mn21. a. Which hydroxide precipitates first? b. What OH2 concentration is needed to initiate precipitation of the first hydroxide? c. What is the concentration of the cat

> Calculate the solubility-product constant for each of the following substances, given that the molar concentrations of their saturated solutions are as indicated:

> Sir William Ramsey (Lord Rayleigh) prepared nitrogen samples by several different methods. The density of each sample was measured as the mass of gas required to fill a particular flask at a certain temperature and pressure. Masses of nitrogen samples pr

> Calculate the molar solubility of ZnCO3 in a solution buffered to a pH of 7.50.

> Calculate the molar solubility of ZnCO3 in a solution buffered to a pH of 7.00.

> Calculate the molar solubility of MnS (pink) in a solution with a constant 3H3O14 of a. 3.00 × 10-5 M b. 2.50 × 10-7 M

> A 0.4723-g sample of primary-standard-grade Na2CO3 required 34.78 mL of an H2SO4 solution to reach the end point in the reaction CO3 22 + 2H1 → H2O + CO21g2 What is the molar concentration of the H2SO4?

> Calculate the concentration of CuS in a solution in which 3H3O14 is held constant at a. 2.0 × 10-1 M b. 2.0 × 10-4 M.

> Calculate the molar solubility of PbS in a solution in which 3H3O14 is held constant at a. 3.0 × 10-1 M b. 3.0 × 10-4 M.

> Calculate the molar solubility of BaSO4 in a solution in which 3H3O14 is a. 3.5 M. b. 0.75 M. c. 0.080 M. d. 0.100 M.

> Calculate the molar solubility of ZnC2O4 in a solution that has a fixed H3O1 concentration of a. 1.0 × 10-6 M. b. 1.0 × 10-7 M. c. 1.0 × 10-9 M. d. 1.0 × 10-11 M.

> Write the mass-balance expressions for a solution that is a. 0.2 M in HF. b. 0.25 M in NH3. c. 0.10 M in H3PO4. d. 0.15 M in Na2HPO4. e. 0.0500 M in HClO2 and 0.100 M in NaClO2. f. 0.12 M in NaF and saturated with CaF2. g. 0.100 M in NaOH and satu

> Neglecting any effects caused by volume changes, would you expect the ionic strength to (1) increase, (2) decrease, or (3) remain essentially unchanged when NaOH is added to a dilute solution of a. magnesium chloride [Mg1OH221s2] forms? b. hydrochlor

> Two different analytical methods were used to determine residual chlorine in sewage effluents. Both methods were used on the same samples, but each sample came from various locations with differing amounts of contact time with the effluent. Two methods w

> Find the amount of the indicated element (in moles) in a. 5.32 g of B2O3. b. 195.7 mg of Na2B4O7 ? 10H2O. c. 4.96 g of Mn3O4. d. 333 mg of CaC2O4.

> List several general properties of activity coefficients.

> Describe the preparation of a. 1.00 L of 0.150 M KMnO4 from the solid reagent. b. 2.50 L of 0.500 M HClO4, starting with a 9.00 M solution of the reagent. c. 400 mL of a solution that is 0.0500 M in I2, starting with MgI2. d. 200 mL of 1.00% (w>v) aq

> Make a distinction between a. activity and activity coefficient. b. thermodynamic and concentration equilibrium constants.

> Design and construct a spreadsheet to calculate activity coefficients in a format similar to Table 8-2. Enter values of aX in cells A3, A4, A5, and so forth, and enter ionic charges in cells B3, B4, B5, and so forth. Enter in cells C2:G2 the same set of

> Calculate the % relative error in hydronium ion concentration by using concentrations instead of activities in calculating the pH of the following buffer solutions using the thermodynamic constants found in Appendix 3. a. 0.175 M HOAc and 0.275 M NaOAc

> Calculate the % relative error in solubility by using concentrations instead of activities for the following compounds in 0.0350 M KNO3 using the thermodynamic solubility products listed in Appendix 2. a. CuCl 1aCu1 5 0.3 nm2 b. Fe1OH22 c. Fe1OH23 d. La

> Calculate the solubilities of the following compounds in a 0.0167 M solution of Ba1NO322 using (1) activities and (2) molar concentrations: a. AgIO3. b. Mg1OH22. c. BaSO4. d. La1IO323.

> Calculate the solubilities of the following compounds in a 0.0275 M solution of Mg1ClO422 using (1) activities and (2) molar concentrations: a. AgSCN. b. PbI2. c. BaSO4. d. Cd2Fe1CN26.

> Use activities to calculate the molar solubility of Zn1OH22 in a. 0.0150 M KCl. b. 0.0250 M K2SO4. c. the solution that results when you mix 40.0 mL of 0.250 M KOH with 60.0 mL of 0.0250 M ZnCl2. d. the solution that results when you mix 20.0 mL of 0.1

> For a solution in which m 5 6.5 3 1022, calculate K9sp for a. AgSCN. b. PbI2. c. La1IO323. d. MgNH4PO4.

> The homogeneity of the chloride level in a water sample from a lake was tested by analyzing portions drawn from the top and from near the bottom of the lake, with the following results in ppm Cl: a. Apply the t test at the 95% confidence level to determ

> Calculate activity coefficients for the species in Problem 8-10 by linear interpolation of the data in Table 8-2.

> Describe the preparation of a. 500 mL of 0.0750 M AgNO3 from the solid reagent. b. 2.00 L of 0.325 M HCl, starting with a 6.00 M solution of the reagent. c. 750 mL of a solution that is 0.0900 M in K1, starting with solid K4Fe1CN26. d. 600 mL of 2.00

> Express the solubility-product constant for each substance in Problem 7-8 in terms of its molar solubility S.

> Use Equation 8-5 to calculate the activity coefficient of

> Calculate the ionic strength of a solution that is a. 0.025 M in FeSO4. b. 0.25 M in 1NH422CrO4. c. 0.25 M in FeCl3 and 0.15 M in FeCl2. d. 0.025 M in La1NO323 and 0.050 M in Fe1NO322.

> What is the numerical value of the activity coefficient of aqueous ammonia 1NH32 at an ionic strength of 0.2?

> Explain why the initial slope for Ca21 in Figure 8-3 is steeper than that for K1?

> Explain why the activity coefficient for a neutral molecule is usually 1

> Explain why the activity coefficient for dissolved ions in water is usually less than that for water itself.

> Neglecting any effects caused by volume changes, would you expect the ionic strength to (1) increase, (2) decrease, or (3) remain essentially unchanged by the addition of iron(III) chloride to a. HCl? b. NaOH? c. AgNO3?

> What is the standard error of a mean? Why is the standard deviation of the mean lower than the standard deviation of the data points in a set?

> Distinguish between a. The sample variance and the population variance. b. The meaning of the word sample as it is used in a chemical and in a statistical sense.

> Write the equilibrium-constant expressions and obtain numerical values for each constant in a. The basic dissociation of aniline, C6H5NH2. b. The acidic dissociation of hypochlorous acid, HClO. c. The acidic dissociation of methyl ammonium hydrochloride

> Differentiate between a. Parameter and statistic. b. Population mean and sample mean. c. Random and systematic error. d. Accuracy and precision.

> Go to http://dx.doi.org/10.18434/T43G6C, where you will find a link to the NIST Statistical Reference Datasets site. Find the Dataset Archives, locate the Univariate Summary Statistics section, and select the Mavro data set. This actual data set is the r

> Calculate a pooled estimate of s from the following spectrophotometric analysis for NTA (nitrilotriacetic acid) in water from the Ohio River:

> Nine samples of illicit heroin preparations were analyzed in duplicate by a gas chromatographic method. The samples can be assumed to have been drawn randomly from the same population. Pool the following data to establish an estimate of s for the procedu

> Describe the steps in a sampling operation.

> State quantitatively the null hypothesis H0 and the alternative hypothesis Ha for the following situations, and describe the type I and type II errors. If these hypotheses were to be tested statistically, comment on whether a one- or two-tailed test woul

> In a volumetric determination of an analyte A, the data obtained and their standard deviations are as follows: From the data, find the coefficient of variation of the final result for the %A that is obtained by using the equation that follows and assumin

> Six bottles of wine of the same variety were analyzed for residual sugar content with the following results: / Evaluate the standard deviation s for each set of data. Pool the data to obtain an absolute standard deviation for t

> Analysis of several plant-food preparations for potassium ion yielded the following data: The preparations were randomly drawn from the same population. Find the mean and standard deviation Ñ• for each sample. Obtain the pooled

> Chapter 22 shows that quantitative molecular absorption spectrometry is based on Beer’s law, which can be written as -log T = εbcX where T is the transmittance of a solution of an analyte X, b is the thickness of the absorbing solution, cX is the molar c

> Calculate the molar concentration of a 20.0% solution (w/w) of KCl that has

> Identify the base on the left and its conjugate acid on the right in the equations for Problem 7-4.

> Chapter 26 describes inductively coupled plasma atomic emission spectrometry. In that method, the number of atoms excited to a particular energy level is a strong function of temperature. For an element of excitation energy E in joules (J), the measured

> The standard deviation in measuring the diameter d of a sphere is ±0.02 cm. What is the standard deviation in the calculated volume V of the sphere if d = 2.35 cm?

> Define a. Sample standard deviation. b. Coefficient of variation. c. Variance. d. Standard error of the mean.

> Calculate the absolute standard deviation and the coefficient of variation for the results of the following calculations. Round each result to include only significant figures. The numbers in parentheses are absolute standard deviations. a. y = log[2.00(

> The color change of a chemical indicator requires an overtitration of 0.03 mL. Calculate the percent relative error if the total volume of titrant is

> What is the object of the sampling step in an analysis?

> Estimate the absolute deviation and the coefficient of variation for the results of the following calculations. Round each result so that it contains only significant digits. The numbers in parentheses are absolute standard deviations. a. y = 3.95(±0.03)

> Name three types of systematic errors.

> Suggest two sources of systematic error and two sources of random error in measuring the length of a 3-m table with a 1-m metal rule.

> Calculate the molar concentration of a solution that is 50.0% NaOH (w/w) and has a specific gravity of 1.52.

> Explain the difference between a. random and systematic error. b. constant and proportional error. c. absolute and relative error. d. mean and median.